R.H. Springer-Miller
D A Chenoweth
A L Paskavitz
A Y H Chang
Amy M. Regish
I E Einarsdottir
Bjorn Bjornsson
Stephen D. McCormick
Jason P. Breves
2020
<p><span>The growth hormone (Gh)/insulin-like growth-factor (Igf)/Igf binding protein (Igfbp) system regulates growth and osmoregulation in salmonid fishes, but how this system interacts with other endocrine systems is largely unknown. Given the well-documented consequences of mounting a glucocorticoid stress response on growth, we hypothesized that cortisol inhibits anabolic processes by modulating the expression of hepatic </span><i>igfbp</i><span> mRNAs. Atlantic salmon (</span><i>Salmo salar</i><span>) parr were implanted intraperitoneally with cortisol implants (0, 10, and 40 μg g</span><sup>−1</sup><span> body weight) and sampled after 3 or 14 days. Cortisol elicited a dose-dependent reduction in specific growth rate (SGR) after 14 days. While plasma Gh and Igf1 levels were unchanged, hepatic </span><i>igf1</i><span> mRNA was diminished and hepatic </span><i>igfbp1b1</i><span> and </span><i>-1b2</i><span> were stimulated by the high cortisol dose. Plasma Igf1 was positively correlated with SGR at 14 days. Hepatic </span><i>gh receptor</i><span> (</span><i>ghr</i><span>), </span><i>igfbp1a</i><span>, </span><i>-2a</i><span>, </span><i>-2b1</i><span>, and </span><i>-2b2</i><span> levels were not impacted by cortisol. Muscle </span><i>igf2</i><span>, but not </span><i>igf1</i><span> or </span><i>ghr</i><span>, levels were stimulated at 3 days by the high cortisol dose. As both cortisol and the Gh/Igf axis promote seawater (SW) tolerance, and particular </span><i>igfbps</i><span> respond to SW exposure, we also assessed whether cortisol coordinates the expression of branchial </span><i>igfbps</i><span> and genes associated with ion transport. Cortisol stimulated branchial </span><i>igfbp5b2</i><span> levels in parallel with Na</span><sup>+</sup><span>/K</span><sup>+</sup><span>-ATPase (NKA) activity and </span><i>nka-α1b</i><span>, </span><i>Na</i><sup><i>+</i></sup><i>/K</i><sup><i>+</i></sup><i>/</i><span>2Cl</span><sup><i>-</i></sup><i>-cotransporter 1</i><span> (</span><i>nkcc1</i><span>), and </span><i>cystic fibrosis transmembrane regulator 1</i><span> (</span><i>cftr1</i><span>) mRNA levels. The collective results indicate that cortisol modulates the growth of juvenile salmon via the regulation of hepatic </span><i>igfbp1s</i><span> whereas no clear links between cortisol and branchial </span><i>igfbps</i><span> previously shown to be salinity-responsive could be established.</span></p>
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10.1016/j.mce.2020.110989
en
Elsevier
Cortisol regulates insulin-like growth-factor binding protein (igfbp) gene expression in Atlantic salmon parr
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